$DE00/56832/RR+0: Control-Register
On read:
+-------+--------------------------------------------------------+
| Bit 7 | ROM bank selector (A15) |
| Bit 6 | 1 = REU compatible memory map active |
| Bit 5 | ROM bank selector (A16) |
| Bit 4 | ROM bank selector (A14) |
| Bit 3 | ROM bank selector (A13) |
| Bit 2 | 1 = Freeze button pressed |
| Bit 1 | AllowBank bit (see $DE01 / Write) |
| Bit 0 | 1 = Flashmode active (jumper set) |
+-------+--------------------------------------------------------+
On write:
+-------+--------------------------------------------------------+
| Bit 7 | ROM bank selector (A15) |
| Bit 6 | 1 = exit from Freeze mode (if not in, no effect) |
| Bit 5 | 0 = select ROM, 1 = select RAM |
| Bit 4 | ROM bank selector (A14) |
| Bit 3 | ROM bank selector (A13) |
| Bit 2 | 1 = disable cartridge |
| Bit 1 | 1 = /EXROM high |
| Bit 0 | 1 = /GAME low |
+-------+--------------------------------------------------------+
Default value is $00(%00000000) ($02 (%00000010) when Flashmode active).